1. Field of the Invention
The present invention concerns a magnetic recording/playback head and, more particularly, a plane head, namely a magnetic head wherein the magnetic poles are located along one and the same plane. A magnetic head of this type can be used particularly in techniques for recording/playback on magnetic tapes. The invention also concerns a method for making a magnetic head of this type.
2. Discussion of the Background
The making of plane magnetic heads, of the shape shown in FIG. 1, is known.
These heads possess a magnetic circuit M having a plane face P. The magnetic poles of the recording head and the gap that separates them are located along this plane P. The recording medium such as a magnetic tape is placed, in the vicinity of the magnetic poles and of the gap E, parallel to the plane P. A magnetic field induction coil, supplied with current through the connections 70 and 71, surround an arm of the magnetic circuit M. As can be seen in FIG. 1, a head of this type has a narrowed portion at the gap E. This narrowed portion is brittle and difficult to make.
The invention concerns a head of this type which is less brittle and easier to make.
Furthermore, in known plane heads, the size of the gap (thickness of 0.2 micrometers and height of one micrometer) necessitates achieving growths of non-plane materials as described, for example, in the French patent application No. 86 14974, filed on 28th Oct., 1986. Thus, as shown in FIG. 2, a magnetic pole P1 is made on a substrate S with a layer of non-magnetic material E placed on a flank of the pole P1. Another layer of magnetic material (P2) is deposited on the unit. Then the upper face of the head is machined to obtain a plane magnetic head as shown in FIG. 3, with the magnetic poles P1 and P2 separated by a gap E.
As can be seen in FIG. 2, the layer of magnetic material forming the magnetic pole P2 must match the shape of the gap E: this disturbs the magnetic properties at the edge of the gap E. The definition of the gap and the discontinuity that it creates in the magnetic field thus get deteriorated, and this happens in a zone extending to a distance equal to some multiples of the height of the gap, measured from the gap.
However, it is essential to make thin layers of a thickness of 2 to 3 micrometers for plane magnetic heads. According to this technique, the magnetic pole P2 is thus dependent on the height of the gap.
The invention provides, according to one variant embodiment, for resolving this difficulty.